The new USB spec is expected to eventually scale throughput beyond 40Gbps

The USB SuperSpeed specification and accompanying hardware are about to undergo a number of major evolutionary makeovers that will leave little room for the Thunderbolt hardware interface to expand in the market.

Both USB SuperSpeed and Thunderbolt have recently undergone version upgrades - USB moved to v3.1 (SuperSpeed+) and Thunderbolt to v2. And both upgrades double the maximum throughput speed -- USB 3.1 to 10Gbps and Thunderbolt 2 to 20Gbps.

But, the USB SuperSpeed specification has a lot of elasticity built into it.

"This tech will scale well beyond 10Gbps," said Rahman Ismail, a USB 3.0 senior architect at Intel. "We believe we already have a protocol that will scale well past 40Gbps."

Other than speed, Thunderbolt 2 has another advantage over USB 3.1 - 10 watts of power compared with USB SuperSpeed's 4.5 watts.

PCI Express and DisplayPort are transported between Thunderbolt controllers over a Thunderbolt cable (Source: Intel Corp.)

But, the USB connector specification is also getting long-awaited improvements that will give users a reversible plug orientation and the opportunity for a more robust cable offering up to 100 watts of power. Again, like Thunderbolt, the new USB Type-C Connector means both the cable and the connector plug are symmetrical and the technology will eventually offer 10 times the power of Thunderbolt 2.

The new USB Type-C Connector specification is expected to be completed in July. A more robust version of the cables, capable of supporting 100 watts of power, are expected later next year.

A USB SuperSpeed+ cable certified for 100 watt power transfer could support an external hard drive and an Ultra-High Definition (UHD) 4K television display, according to Jeff Ravencraft, president of the USB Implementers Forum (USB-IF).

USB SuperSpeed 3.1 products are expected to hit the market in early 2015 -- possibly as early as this Christmas, Ravencraft said.

"It's revolutionary. It's like what happened with the phone, when companies standardized on the Micro USB port for charging for consumers.... They no longer had to have custom fit a cable for every phone they bought," Ravencraft said.

Apple continues to be the leading adopter of Thunderbolt connector technology for its desktop and laptops, but it offers it right alongside USB. Beginning last year, HP also adopted Thunderbolt alongside USB 3.0 for a half dozen workstations, but it has yet to add it to any consumer devices.

"If they continue to support it, it will survive," O'Rourke said. "USB's installed base is in the billions. Thunderbolt's biggest problem is a relatively small installed base, in the tens of millions. Adding a higher data throughput, and a more expensive option, is unlikely to change that."

One big draw for Thunderbolt was that its added bandwidth that allowed both display and data throughput on a single cable.

For example, connecting an external hard drive via a USB 3.1 certified piece of hardware will offer 4.5W of power plus about 10Gbps of data (before overhead). By comparison, Thunderbolt 2 offers 10W of power plus 16Gbps of data (before PCIe overhead).